From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jan Kara <jack@suse.cz>
Subject: Re: [PATCH 1/7] fsfreeze: Prevent emergency thaw from looping
 infinitely
Date: Tue, 10 Jul 2012 14:08:58 +0200
Message-ID: <20120710120858.GD13539@quack.suse.cz>
References: <1341908216.11559.6.camel@nexus.lab.ntt.co.jp>
 <1341908457.11559.9.camel@nexus.lab.ntt.co.jp>
Mime-Version: 1.0
Content-Type: text/plain; charset=iso-8859-1
Content-Transfer-Encoding: QUOTED-PRINTABLE
Cc: Al Viro <viro@zeniv.linux.org.uk>,
	Dave Chinner <dchinner@redhat.com>,
	Christoph Hellwig <hch@infradead.org>,
	linux-fsdevel@vger.kernel.org
To: Fernando Luis =?iso-8859-1?Q?V=E1zquez?= Cao
	<fernando_b1@lab.ntt.co.jp>
Return-path: <linux-fsdevel-owner@vger.kernel.org>
Received: from cantor2.suse.de ([195.135.220.15]:36997 "EHLO mx2.suse.de"
	rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
	id S1752460Ab2GJMJC (ORCPT <rfc822;linux-fsdevel@vger.kernel.org>);
	Tue, 10 Jul 2012 08:09:02 -0400
Content-Disposition: inline
In-Reply-To: <1341908457.11559.9.camel@nexus.lab.ntt.co.jp>
Sender: linux-fsdevel-owner@vger.kernel.org
List-ID: <linux-fsdevel.vger.kernel.org>

On Tue 10-07-12 17:20:57, Fernando Luis V=E1zquez Cao wrote:
> The thawing of a filesystem through sysrq-j loops infinitely as it
> incorrectly detects a thawed filesytsem as frozen and tries to
> unfreeze repeatedly. This is a regression caused by
> 4504230a71566785a05d3e6b53fa1ee071b864eb ("freeze_bdev: grab active
> reference to frozen superblocks") in that it no longer returned
> -EINVAL for superblocks that were not frozen.
  Umm, I don't think above mentioned commit is really guilty. Also I th=
ink
your patch breaks thawing of a block device without mounted filesystem =
-
you end up returning EINVAL for that...

								Honza
>=20
> Return -EINVAL when the filesystem is already unfrozen to avoid this
> problem.
>=20
> Cc: Christoph Hellwig <hch@infradead.org>
> Signed-off-by: Dave Chinner <dchinner@redhat.com>
> Signed-off-by: Fernando Luis Vazquez Cao <fernando@oss.ntt.co.jp>
> ---
>=20
> diff -urNp linux-3.5-rc4-orig/fs/block_dev.c linux-3.5-rc4/fs/block_d=
ev.c
> --- linux-3.5-rc4-orig/fs/block_dev.c	2012-06-27 12:00:47.694616000 +=
0900
> +++ linux-3.5-rc4/fs/block_dev.c	2012-06-29 13:38:23.841352532 +0900
> @@ -319,22 +319,20 @@ int thaw_bdev(struct block_device *bdev,
>  	if (!bdev->bd_fsfreeze_count)
>  		goto out;
> =20
> -	error =3D 0;
> -	if (--bdev->bd_fsfreeze_count > 0)
> +	if (--bdev->bd_fsfreeze_count > 0) {
> +		error =3D 0;
>  		goto out;
> +	}
> =20
>  	if (!sb)
>  		goto out;
> =20
>  	error =3D thaw_super(sb);
> -	if (error) {
> +	if (error)
>  		bdev->bd_fsfreeze_count++;
> -		mutex_unlock(&bdev->bd_fsfreeze_mutex);
> -		return error;
> -	}
>  out:
>  	mutex_unlock(&bdev->bd_fsfreeze_mutex);
> -	return 0;
> +	return error;
>  }
>  EXPORT_SYMBOL(thaw_bdev);
> =20
>=20
>=20
> --
> To unsubscribe from this list: send the line "unsubscribe linux-fsdev=
el" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
--=20
Jan Kara <jack@suse.cz>
SUSE Labs, CR
--
To unsubscribe from this list: send the line "unsubscribe linux-fsdevel=
" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html